Residents in the Borden Apartments on Fourth Street were evacuated late Saturday morning because of a gas leak that reached dangerous levels.

Fire Department District Chief James Mellen said fire units responded to the area of Fourth and Hartwell streets around 11:15 a.m. after calls of an odor of gas.

Mellen said an investigation determined a gas leak in an unknown area under Hartwell Street. He said gas levels in the adjacent building at 4 Hartwell St. — which houses the Raw Martini bar — were determined to be high enough to cause an explosion. He said elevated levels were also found in the Borden Apartments at 58 Fourth St., causing the evacuation. Mellen said a bus from the Southeastern Regional Transit Authority was used to transport residents from the area.

Residents were allowed to return to the building around 3 p.m.

“The residents are being allowed back into the building, and we’re working on venting the underground electrical conduit so that we can turn the electricity back on for residents,” Mellen said.

A portion of the road where Hartwell and Fourth streets intersect was being dug up Saturday afternoon, and sections of the two roads were closed to traffic. Mellen said he expected power to be restored and the road to be reopened within a couple of hours.

Efforts to eliminate the potential danger associated with the leak resulted in electricity being shut off in various part of the city. Calls regarding elevators being stuck from the nearby Borden East apartments on Borden Street and the building housing Laser Gate on Plymouth Avenue resulted in an additional Fire Department response to those locations.

“Turning the power off to these buildings resulted in the power turning off to other buildings and caused some additional problems, but it’s better then watching these buildings get destroyed,” Mellen said.